The invention relates to auxiliary devices for the reduction of the emission of pollutants by spark ignition engines.
More particularly, the invention relates to such devices applied to automotive engines operating in the intermittent mode characteristic of traffic conditions in and near large urban areas.
Devices of the prior art, including those disclosed by the Inventor, have had some success in reducing the emission of noxious components in the exhaust of automobile engines and have enabled the manufacturers of such engines to meet the current standards imposed by the United States on such emissions.
If the specifications to be imposed in the period beginning after 1974 are to be met, the emission of pollutants in certain operating regimes of the automobile engine will have to be reduced. More particularly, the concentration of unburned hydrocarbons and of nitrogen oxides at speeds and operating cycles corresponding to heavy traffic conditions will have to be improved.
It is, therefore, a primary purpose of the invention to reduce the proportion of unburned hydrocarbon fuel in the exhaust of automobile engines when the vehicle is coasting with the throttle-valve closed.
It is another purpose of the invention to reduce the emission of nitrogen oxides generally in the exhaust of automobile engines in the speed ranges encountered in urban and suburban traffic.
It is a further purpose of the invention to teach the construction of devices to achieve the above purposes and compatible with the fuel systems of internal combustion engines with spark ignition; such devices being equally applicable to carburetor and direct injection systems.